Use a ReturnedValue for Managed::call()

Change-Id: Ief2d75e9789dd367c603d90dc0fe5316a0d055e3
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

34 files changed, 162 insertions, 127 deletions

diff --git a/src/qml/jsruntime/qv4argumentsobject.cpp b/src/qml/jsruntime/qv4argumentsobject.cpp
index 5a53c0fc3e..89b6f49f1d 100644
--- a/src/qml/jsruntime/qv4argumentsobject.cpp
+++ b/src/qml/jsruntime/qv4argumentsobject.cpp
@@ -148,7 +148,7 @@ bool ArgumentsObject::defineOwnProperty(ExecutionContext *ctx, uint index, const
 
 DEFINE_MANAGED_VTABLE(ArgumentsGetterFunction);
 
-Value ArgumentsGetterFunction::call(Managed *getter, CallData *callData)
+ReturnedValue ArgumentsGetterFunction::call(Managed *getter, CallData *callData)
 {
     ArgumentsGetterFunction *g = static_cast<ArgumentsGetterFunction *>(getter);
     Object *that = callData->thisObject.asObject();
@@ -159,12 +159,12 @@ Value ArgumentsGetterFunction::call(Managed *getter, CallData *callData)
         getter->engine()->current->throwTypeError();
 
     assert(g->index < o->context->argumentCount);
-    return o->context->argument(g->index);
+    return o->context->argument(g->index).asReturnedValue();
 }
 
 DEFINE_MANAGED_VTABLE(ArgumentsSetterFunction);
 
-Value ArgumentsSetterFunction::call(Managed *setter, CallData *callData)
+ReturnedValue ArgumentsSetterFunction::call(Managed *setter, CallData *callData)
 {
     ArgumentsSetterFunction *s = static_cast<ArgumentsSetterFunction *>(setter);
     Object *that = callData->thisObject.asObject();
@@ -176,7 +176,7 @@ Value ArgumentsSetterFunction::call(Managed *setter, CallData *callData)
 
     assert(s->index < o->context->argumentCount);
     o->context->arguments[s->index] = callData->argc ? callData->args[0] : Value::undefinedValue();
-    return Value::undefinedValue();
+    return Value::undefinedValue().asReturnedValue();
 }
 
 void ArgumentsObject::markObjects(Managed *that)
diff --git a/src/qml/jsruntime/qv4argumentsobject_p.h b/src/qml/jsruntime/qv4argumentsobject_p.h
index 66ee22c953..dec2f25c01 100644
--- a/src/qml/jsruntime/qv4argumentsobject_p.h
+++ b/src/qml/jsruntime/qv4argumentsobject_p.h
@@ -55,7 +55,7 @@ struct ArgumentsGetterFunction: FunctionObject
     ArgumentsGetterFunction(ExecutionContext *scope, uint index)
         : FunctionObject(scope), index(index) { vtbl = &static_vtbl; }
 
-    static Value call(Managed *that, CallData *d);
+    static ReturnedValue call(Managed *that, CallData *d);
 
 protected:
     static const ManagedVTable static_vtbl;
@@ -68,7 +68,7 @@ struct ArgumentsSetterFunction: FunctionObject
     ArgumentsSetterFunction(ExecutionContext *scope, uint index)
         : FunctionObject(scope), index(index) { vtbl = &static_vtbl; }
 
-    static Value call(Managed *that, CallData *callData);
+    static ReturnedValue call(Managed *that, CallData *callData);
 
 protected:
     static const ManagedVTable static_vtbl;
diff --git a/src/qml/jsruntime/qv4arrayobject.cpp b/src/qml/jsruntime/qv4arrayobject.cpp
index e3b08f5941..58a2f256cc 100644
--- a/src/qml/jsruntime/qv4arrayobject.cpp
+++ b/src/qml/jsruntime/qv4arrayobject.cpp
@@ -80,9 +80,9 @@ Value ArrayCtor::construct(Managed *m, CallData *callData)
     return Value::fromObject(a);
 }
 
-Value ArrayCtor::call(Managed *that, CallData *callData)
+ReturnedValue ArrayCtor::call(Managed *that, CallData *callData)
 {
-    return construct(that, callData);
+    return construct(that, callData).asReturnedValue();
 }
 
 ArrayPrototype::ArrayPrototype(InternalClass *ic)
@@ -140,7 +140,7 @@ Value ArrayPrototype::method_toString(SimpleCallContext *ctx)
     if (f) {
         ScopedCallData d(ctx->engine, 0);
         d->thisObject = ctx->thisObject;
-        return f->call(d);
+        return Value::fromReturnedValue(f->call(d));
     }
     return ObjectPrototype::method_toString(ctx);
 }
@@ -648,7 +648,7 @@ Value ArrayPrototype::method_every(SimpleCallContext *ctx)
         callData->args[1] = Value::fromDouble(k);
         callData->args[2] = Value::fromObject(instance);
         callData->thisObject = thisArg;
-        Value r = callback->call(callData);
+        Value r = Value::fromReturnedValue(callback->call(callData));
         ok = r.toBoolean();
     }
     return Value::fromBoolean(ok);
@@ -677,7 +677,7 @@ Value ArrayPrototype::method_some(SimpleCallContext *ctx)
         callData->args[0] = v;
         callData->args[1] = Value::fromDouble(k);
         callData->args[2] = Value::fromObject(instance);
-        Value r = callback->call(callData);
+        Value r = Value::fromReturnedValue(callback->call(callData));
         if (r.toBoolean())
             return Value::fromBoolean(true);
     }
@@ -714,6 +714,7 @@ Value ArrayPrototype::method_forEach(SimpleCallContext *ctx)
 
 Value ArrayPrototype::method_map(SimpleCallContext *ctx)
 {
+    ValueScope scope(ctx);
     Object *instance = ctx->thisObject.toObject(ctx);
 
     uint len = getLength(ctx, instance);
@@ -728,18 +729,20 @@ Value ArrayPrototype::method_map(SimpleCallContext *ctx)
     a->arrayReserve(len);
     a->setArrayLengthUnchecked(len);
 
+    ScopedValue mapped(scope);
+    ScopedCallData callData(ctx->engine, 3);
+    callData->thisObject = thisArg;
+    callData->args[2] = Value::fromObject(instance);
+
     for (uint k = 0; k < len; ++k) {
         bool exists;
         Value v = instance->getIndexed(k, &exists);
         if (!exists)
             continue;
 
-        ScopedCallData callData(ctx->engine, 3);
-        callData->thisObject = thisArg;
         callData->args[0] = v;
         callData->args[1] = Value::fromDouble(k);
-        callData->args[2] = Value::fromObject(instance);
-        Value mapped = callback->call(callData);
+        mapped = callback->call(callData);
         a->arraySet(k, mapped);
     }
     return Value::fromObject(a);
@@ -747,6 +750,7 @@ Value ArrayPrototype::method_map(SimpleCallContext *ctx)
 
 Value ArrayPrototype::method_filter(SimpleCallContext *ctx)
 {
+    ValueScope scope(ctx);
     Object *instance = ctx->thisObject.toObject(ctx);
 
     uint len = getLength(ctx, instance);
@@ -760,6 +764,11 @@ Value ArrayPrototype::method_filter(SimpleCallContext *ctx)
     ArrayObject *a = ctx->engine->newArrayObject();
     a->arrayReserve(len);
 
+    ScopedValue selected(scope);
+    ScopedCallData callData(ctx->engine, 3);
+    callData->thisObject = thisArg;
+    callData->args[2] = Value::fromObject(instance);
+
     uint to = 0;
     for (uint k = 0; k < len; ++k) {
         bool exists;
@@ -767,13 +776,10 @@ Value ArrayPrototype::method_filter(SimpleCallContext *ctx)
         if (!exists)
             continue;
 
-        ScopedCallData callData(ctx->engine, 3);
-        callData->thisObject = thisArg;
         callData->args[0] = v;
         callData->args[1] = Value::fromDouble(k);
-        callData->args[2] = Value::fromObject(instance);
-        Value selected = callback->call(callData);
-        if (selected.toBoolean()) {
+        selected = callback->call(callData);
+        if (selected->toBoolean()) {
             a->arraySet(to, v);
             ++to;
         }
@@ -783,6 +789,7 @@ Value ArrayPrototype::method_filter(SimpleCallContext *ctx)
 
 Value ArrayPrototype::method_reduce(SimpleCallContext *ctx)
 {
+    ValueScope scope(ctx);
     Object *instance = ctx->thisObject.toObject(ctx);
 
     uint len = getLength(ctx, instance);
@@ -792,7 +799,7 @@ Value ArrayPrototype::method_reduce(SimpleCallContext *ctx)
         ctx->throwTypeError();
 
     uint k = 0;
-    Value acc;
+    ScopedValue acc(scope);
     if (ctx->argumentCount > 1) {
         acc = ctx->argument(1);
     } else {
@@ -807,16 +814,18 @@ Value ArrayPrototype::method_reduce(SimpleCallContext *ctx)
             ctx->throwTypeError();
     }
 
+    ScopedCallData callData(ctx->engine, 4);
+    callData->thisObject = Value::undefinedValue();
+    callData->args[0] = acc;
+    callData->args[3] = Value::fromObject(instance);
+
     while (k < len) {
         bool kPresent;
         Value v = instance->getIndexed(k, &kPresent);
         if (kPresent) {
-            ScopedCallData callData(ctx->engine, 4);
-            callData->thisObject = Value::undefinedValue();
             callData->args[0] = acc;
             callData->args[1] = v;
             callData->args[2] = Value::fromDouble(k);
-            callData->args[3] = Value::fromObject(instance);
             acc = callback->call(callData);
         }
         ++k;
@@ -826,6 +835,7 @@ Value ArrayPrototype::method_reduce(SimpleCallContext *ctx)
 
 Value ArrayPrototype::method_reduceRight(SimpleCallContext *ctx)
 {
+    ValueScope scope(ctx);
     Object *instance = ctx->thisObject.toObject(ctx);
 
     uint len = getLength(ctx, instance);
@@ -841,7 +851,7 @@ Value ArrayPrototype::method_reduceRight(SimpleCallContext *ctx)
     }
 
     uint k = len;
-    Value acc;
+    ScopedValue acc(scope);
     if (ctx->argumentCount > 1) {
         acc = ctx->argument(1);
     } else {
@@ -856,16 +866,17 @@ Value ArrayPrototype::method_reduceRight(SimpleCallContext *ctx)
             ctx->throwTypeError();
     }
 
+    ScopedCallData callData(ctx->engine, 4);
+    callData->thisObject = Value::undefinedValue();
+    callData->args[3] = Value::fromObject(instance);
+
     while (k > 0) {
         bool kPresent;
         Value v = instance->getIndexed(k - 1, &kPresent);
         if (kPresent) {
-            ScopedCallData callData(ctx->engine, 4);
-            callData->thisObject = Value::undefinedValue();
             callData->args[0] = acc;
             callData->args[1] = v;
             callData->args[2] = Value::fromDouble(k - 1);
-            callData->args[3] = Value::fromObject(instance);
             acc = callback->call(callData);
         }
         --k;
diff --git a/src/qml/jsruntime/qv4arrayobject_p.h b/src/qml/jsruntime/qv4arrayobject_p.h
index 354ddd0380..e8a8ddda22 100644
--- a/src/qml/jsruntime/qv4arrayobject_p.h
+++ b/src/qml/jsruntime/qv4arrayobject_p.h
@@ -54,7 +54,7 @@ struct ArrayCtor: FunctionObject
     ArrayCtor(ExecutionContext *scope);
 
     static Value construct(Managed *m, CallData *callData);
-    static Value call(Managed *that, CallData *callData);
+    static ReturnedValue call(Managed *that, CallData *callData);
 
 protected:
     static const ManagedVTable static_vtbl;
diff --git a/src/qml/jsruntime/qv4booleanobject.cpp b/src/qml/jsruntime/qv4booleanobject.cpp
index 6b77db3ca7..aa5ebbd38c 100644
--- a/src/qml/jsruntime/qv4booleanobject.cpp
+++ b/src/qml/jsruntime/qv4booleanobject.cpp
@@ -57,10 +57,10 @@ Value BooleanCtor::construct(Managed *m, CallData *callData)
     return Value::fromObject(m->engine()->newBooleanObject(Value::fromBoolean(n)));
 }
 
-Value BooleanCtor::call(Managed *, CallData *callData)
+ReturnedValue BooleanCtor::call(Managed *, CallData *callData)
 {
     bool value = callData->argc ? callData->args[0].toBoolean() : 0;
-    return Value::fromBoolean(value);
+    return Value::fromBoolean(value).asReturnedValue();
 }
 
 void BooleanPrototype::init(ExecutionContext *ctx, const Value &ctor)
diff --git a/src/qml/jsruntime/qv4booleanobject_p.h b/src/qml/jsruntime/qv4booleanobject_p.h
index 35ecf25b6f..7cdd2d741b 100644
--- a/src/qml/jsruntime/qv4booleanobject_p.h
+++ b/src/qml/jsruntime/qv4booleanobject_p.h
@@ -54,7 +54,7 @@ struct BooleanCtor: FunctionObject
     BooleanCtor(ExecutionContext *scope);
 
     static Value construct(Managed *, CallData *callData);
-    static Value call(Managed *that, CallData *callData);
+    static ReturnedValue call(Managed *that, CallData *callData);
 
 protected:
     static const ManagedVTable static_vtbl;
diff --git a/src/qml/jsruntime/qv4dateobject.cpp b/src/qml/jsruntime/qv4dateobject.cpp
index 1ef4aec246..ec4c0028a0 100644
--- a/src/qml/jsruntime/qv4dateobject.cpp
+++ b/src/qml/jsruntime/qv4dateobject.cpp
@@ -693,10 +693,10 @@ Value DateCtor::construct(Managed *m, CallData *callData)
     return Value::fromObject(o);
 }
 
-Value DateCtor::call(Managed *m, CallData *)
+ReturnedValue DateCtor::call(Managed *m, CallData *)
 {
     double t = currentTime();
-    return Value::fromString(m->engine()->current, ToString(t));
+    return Value::fromString(m->engine()->current, ToString(t)).asReturnedValue();
 }
 
 void DatePrototype::init(ExecutionContext *ctx, const Value &ctor)
@@ -1305,7 +1305,7 @@ Value DatePrototype::method_toJSON(SimpleCallContext *ctx)
 
     ScopedCallData callData(ctx->engine, 0);
     callData->thisObject = ctx->thisObject;
-    return toIso->call(callData);
+    return Value::fromReturnedValue(toIso->call(callData));
 }
 
 void DatePrototype::timezoneUpdated()
diff --git a/src/qml/jsruntime/qv4dateobject_p.h b/src/qml/jsruntime/qv4dateobject_p.h
index 573326adc4..eff47e60f2 100644
--- a/src/qml/jsruntime/qv4dateobject_p.h
+++ b/src/qml/jsruntime/qv4dateobject_p.h
@@ -67,7 +67,7 @@ struct DateCtor: FunctionObject
     DateCtor(ExecutionContext *scope);
 
     static Value construct(Managed *, CallData *callData);
-    static Value call(Managed *that, CallData *);
+    static ReturnedValue call(Managed *that, CallData *);
 
 protected:
     static const ManagedVTable static_vtbl;
diff --git a/src/qml/jsruntime/qv4errorobject.cpp b/src/qml/jsruntime/qv4errorobject.cpp
index 96c5f67120..0f08d6e758 100644
--- a/src/qml/jsruntime/qv4errorobject.cpp
+++ b/src/qml/jsruntime/qv4errorobject.cpp
@@ -245,9 +245,9 @@ Value ErrorCtor::construct(Managed *m, CallData *callData)
     return Value::fromObject(m->engine()->newErrorObject(callData->argc ? callData->args[0] : Value::undefinedValue()));
 }
 
-Value ErrorCtor::call(Managed *that, CallData *callData)
+ReturnedValue ErrorCtor::call(Managed *that, CallData *callData)
 {
-    return that->construct(callData);
+    return that->construct(callData).asReturnedValue();
 }
 
 EvalErrorCtor::EvalErrorCtor(ExecutionContext *scope)
diff --git a/src/qml/jsruntime/qv4errorobject_p.h b/src/qml/jsruntime/qv4errorobject_p.h
index 1d82bb7ba2..7ccb9cb4cf 100644
--- a/src/qml/jsruntime/qv4errorobject_p.h
+++ b/src/qml/jsruntime/qv4errorobject_p.h
@@ -115,7 +115,7 @@ struct ErrorCtor: FunctionObject
     ErrorCtor(ExecutionContext *scope, String *name);
 
     static Value construct(Managed *, CallData *callData);
-    static Value call(Managed *that, CallData *callData);
+    static ReturnedValue call(Managed *that, CallData *callData);
 
 protected:
     static const ManagedVTable static_vtbl;
diff --git a/src/qml/jsruntime/qv4functionobject.cpp b/src/qml/jsruntime/qv4functionobject.cpp
index c87fad62b3..a2fb4d270b 100644
--- a/src/qml/jsruntime/qv4functionobject.cpp
+++ b/src/qml/jsruntime/qv4functionobject.cpp
@@ -166,9 +166,9 @@ Value FunctionObject::construct(Managed *that, CallData *)
     return Value::fromObject(obj);
 }
 
-Value FunctionObject::call(Managed *, CallData *)
+ReturnedValue FunctionObject::call(Managed *, CallData *)
 {
-    return Value::undefinedValue();
+    return Value::undefinedValue().asReturnedValue();
 }
 
 void FunctionObject::markObjects(Managed *that)
@@ -253,9 +253,9 @@ Value FunctionCtor::construct(Managed *that, CallData *callData)
 }
 
 // 15.3.1: This is equivalent to new Function(...)
-Value FunctionCtor::call(Managed *that, CallData *callData)
+ReturnedValue FunctionCtor::call(Managed *that, CallData *callData)
 {
-    return construct(that, callData);
+    return construct(that, callData).asReturnedValue();
 }
 
 FunctionPrototype::FunctionPrototype(InternalClass *ic)
@@ -324,7 +324,7 @@ Value FunctionPrototype::method_apply(SimpleCallContext *ctx)
     }
 
     callData->thisObject = thisArg;
-    return o->call(callData);
+    return Value::fromReturnedValue(o->call(callData));
 }
 
 Value FunctionPrototype::method_call(SimpleCallContext *ctx)
@@ -341,7 +341,7 @@ Value FunctionPrototype::method_call(SimpleCallContext *ctx)
                   ctx->arguments + ctx->argumentCount, callData->args);
     }
     callData->thisObject = thisArg;
-    return o->call(callData);
+    return Value::fromReturnedValue(o->call(callData));
 }
 
 Value FunctionPrototype::method_bind(SimpleCallContext *ctx)
@@ -434,7 +434,7 @@ Value ScriptFunction::construct(Managed *that, CallData *callData)
     return Value::fromObject(obj);
 }
 
-Value ScriptFunction::call(Managed *that, CallData *callData)
+ReturnedValue ScriptFunction::call(Managed *that, CallData *callData)
 {
     ScriptFunction *f = static_cast<ScriptFunction *>(that);
     void *stackSpace;
@@ -460,7 +460,7 @@ Value ScriptFunction::call(Managed *that, CallData *callData)
     }
     CHECK_JS_STACK(f->scope);
     ctx->engine->popContext();
-    return result;
+    return result.asReturnedValue();
 }
 
 DEFINE_MANAGED_VTABLE(SimpleScriptFunction);
@@ -531,7 +531,7 @@ Value SimpleScriptFunction::construct(Managed *that, CallData *callData)
     return Value::fromObject(obj);
 }
 
-Value SimpleScriptFunction::call(Managed *that, CallData *callData)
+ReturnedValue SimpleScriptFunction::call(Managed *that, CallData *callData)
 {
     SimpleScriptFunction *f = static_cast<SimpleScriptFunction *>(that);
     void *stackSpace = alloca(requiredMemoryForExecutionContectSimple(f));
@@ -557,7 +557,7 @@ Value SimpleScriptFunction::call(Managed *that, CallData *callData)
     }
     CHECK_JS_STACK(f->scope);
     ctx->engine->popContext();
-    return result;
+    return result.asReturnedValue();
 }
 
 
@@ -579,7 +579,7 @@ Value BuiltinFunctionOld::construct(Managed *f, CallData *)
     return Value::undefinedValue();
 }
 
-Value BuiltinFunctionOld::call(Managed *that, CallData *callData)
+ReturnedValue BuiltinFunctionOld::call(Managed *that, CallData *callData)
 {
     BuiltinFunctionOld *f = static_cast<BuiltinFunctionOld *>(that);
     ExecutionEngine *v4 = f->engine();
@@ -603,10 +603,10 @@ Value BuiltinFunctionOld::call(Managed *that, CallData *callData)
     }
 
     context->engine->popContext();
-    return result;
+    return result.asReturnedValue();
 }
 
-Value IndexedBuiltinFunction::call(Managed *that, CallData *callData)
+ReturnedValue IndexedBuiltinFunction::call(Managed *that, CallData *callData)
 {
     IndexedBuiltinFunction *f = static_cast<IndexedBuiltinFunction *>(that);
     ExecutionEngine *v4 = f->engine();
@@ -630,7 +630,7 @@ Value IndexedBuiltinFunction::call(Managed *that, CallData *callData)
     }
 
     context->engine->popContext();
-    return result;
+    return result.asReturnedValue();
 }
 
 DEFINE_MANAGED_VTABLE(IndexedBuiltinFunction);
@@ -661,7 +661,7 @@ void BoundFunction::destroy(Managed *that)
     static_cast<BoundFunction *>(that)->~BoundFunction();
 }
 
-Value BoundFunction::call(Managed *that, CallData *dd)
+ReturnedValue BoundFunction::call(Managed *that, CallData *dd)
 {
     BoundFunction *f = static_cast<BoundFunction *>(that);
 
diff --git a/src/qml/jsruntime/qv4functionobject_p.h b/src/qml/jsruntime/qv4functionobject_p.h
index d694d28462..bad62af6f3 100644
--- a/src/qml/jsruntime/qv4functionobject_p.h
+++ b/src/qml/jsruntime/qv4functionobject_p.h
@@ -118,11 +118,11 @@ struct Q_QML_EXPORT FunctionObject: Object {
     Value newInstance();
 
     static Value construct(Managed *that, CallData *);
-    static Value call(Managed *that, CallData *d);
+    static ReturnedValue call(Managed *that, CallData *d);
     inline Value construct(CallData *callData) {
         return vtbl->construct(this, callData);
     }
-    inline Value call(CallData *callData) {
+    inline ReturnedValue call(CallData *callData) {
         return vtbl->call(this, callData);
     }
 
@@ -143,7 +143,7 @@ struct FunctionCtor: FunctionObject
     FunctionCtor(ExecutionContext *scope);
 
     static Value construct(Managed *that, CallData *callData);
-    static Value call(Managed *that, CallData *callData);
+    static ReturnedValue call(Managed *that, CallData *callData);
 
 protected:
     static const ManagedVTable static_vtbl;
@@ -166,7 +166,7 @@ struct BuiltinFunctionOld: FunctionObject {
     BuiltinFunctionOld(ExecutionContext *scope, String *name, Value (*code)(SimpleCallContext *));
 
     static Value construct(Managed *, CallData *);
-    static Value call(Managed *that, CallData *callData);
+    static ReturnedValue call(Managed *that, CallData *callData);
 
 protected:
     static const ManagedVTable static_vtbl;
@@ -194,7 +194,7 @@ struct IndexedBuiltinFunction: FunctionObject
         return Value::undefinedValue();
     }
 
-    static Value call(Managed *that, CallData *callData);
+    static ReturnedValue call(Managed *that, CallData *callData);
 };
 
 
@@ -202,7 +202,7 @@ struct ScriptFunction: FunctionObject {
     ScriptFunction(ExecutionContext *scope, Function *function);
 
     static Value construct(Managed *, CallData *callData);
-    static Value call(Managed *that, CallData *callData);
+    static ReturnedValue call(Managed *that, CallData *callData);
 
 protected:
     static const ManagedVTable static_vtbl;
@@ -212,7 +212,7 @@ struct SimpleScriptFunction: FunctionObject {
     SimpleScriptFunction(ExecutionContext *scope, Function *function);
 
     static Value construct(Managed *, CallData *callData);
-    static Value call(Managed *that, CallData *callData);
+    static ReturnedValue call(Managed *that, CallData *callData);
 
 protected:
     static const ManagedVTable static_vtbl;
@@ -228,7 +228,7 @@ struct BoundFunction: FunctionObject {
 
 
     static Value construct(Managed *, CallData *d);
-    static Value call(Managed *that, CallData *dd);
+    static ReturnedValue call(Managed *that, CallData *dd);
 
     static const ManagedVTable static_vtbl;
     static void destroy(Managed *);
diff --git a/src/qml/jsruntime/qv4globalobject.cpp b/src/qml/jsruntime/qv4globalobject.cpp
index 6176893d68..e6f3de712d 100644
--- a/src/qml/jsruntime/qv4globalobject.cpp
+++ b/src/qml/jsruntime/qv4globalobject.cpp
@@ -354,10 +354,10 @@ EvalFunction::EvalFunction(ExecutionContext *scope)
     defineReadonlyProperty(scope->engine->id_length, Value::fromInt32(1));
 }
 
-Value EvalFunction::evalCall(Value /*thisObject*/, Value *args, int argc, bool directCall)
+ReturnedValue EvalFunction::evalCall(Value /*thisObject*/, Value *args, int argc, bool directCall)
 {
     if (argc < 1)
-        return Value::undefinedValue();
+        return Value::undefinedValue().asReturnedValue();
 
     ExecutionContext *parentContext = engine()->current;
     ExecutionEngine *engine = parentContext->engine;
@@ -371,7 +371,7 @@ Value EvalFunction::evalCall(Value /*thisObject*/, Value *args, int argc, bool d
     }
 
     if (!args[0].isString())
-        return args[0];
+        return args[0].asReturnedValue();
 
     const QString code = args[0].stringValue()->toQString();
     bool inheritContext = !ctx->strictMode;
@@ -383,7 +383,7 @@ Value EvalFunction::evalCall(Value /*thisObject*/, Value *args, int argc, bool d
 
     Function *function = script.function();
     if (!function)
-        return Value::undefinedValue();
+        return Value::undefinedValue().asReturnedValue();
 
     strictMode = function->isStrict() || (ctx->strictMode);
 
@@ -436,11 +436,11 @@ Value EvalFunction::evalCall(Value /*thisObject*/, Value *args, int argc, bool d
     while (engine->current != parentContext)
         engine->popContext();
 
-    return result;
+    return result.asReturnedValue();
 }
 
 
-Value EvalFunction::call(Managed *that, CallData *callData)
+ReturnedValue EvalFunction::call(Managed *that, CallData *callData)
 {
     // indirect call
     // ### const_cast
diff --git a/src/qml/jsruntime/qv4globalobject_p.h b/src/qml/jsruntime/qv4globalobject_p.h
index b777bf8915..c58078c26d 100644
--- a/src/qml/jsruntime/qv4globalobject_p.h
+++ b/src/qml/jsruntime/qv4globalobject_p.h
@@ -52,10 +52,10 @@ struct Q_QML_EXPORT EvalFunction : FunctionObject
 {
     EvalFunction(ExecutionContext *scope);
 
-    Value evalCall(Value thisObject, Value *args, int argc, bool directCall);
+    ReturnedValue evalCall(Value thisObject, Value *args, int argc, bool directCall);
 
     using Managed::construct;
-    static Value call(Managed *that, CallData *callData);
+    static ReturnedValue call(Managed *that, CallData *callData);
 
 protected:
     static const ManagedVTable static_vtbl;
diff --git a/src/qml/jsruntime/qv4jsonobject.cpp b/src/qml/jsruntime/qv4jsonobject.cpp
index 32b7ba73cc..3048d00ddb 100644
--- a/src/qml/jsruntime/qv4jsonobject.cpp
+++ b/src/qml/jsruntime/qv4jsonobject.cpp
@@ -706,7 +706,7 @@ QString Stringify::Str(const QString &key, Value value)
             ScopedCallData callData(ctx->engine, 1);
             callData->thisObject = value;
             callData->args[0] = Value::fromString(ctx, key);
-            value = toJSON->call(callData);
+            value = Value::fromReturnedValue(toJSON->call(callData));
         }
     }
 
@@ -718,7 +718,7 @@ QString Stringify::Str(const QString &key, Value value)
         callData->args[0] = Value::fromString(ctx, key);
         callData->args[1] = value;
         callData->thisObject = holderValue;
-        value = replacerFunction->call(callData);
+        value = Value::fromReturnedValue(replacerFunction->call(callData));
     }
 
     if (Object *o = value.asObject()) {
diff --git a/src/qml/jsruntime/qv4lookup.cpp b/src/qml/jsruntime/qv4lookup.cpp
index 2cffa55642..b630bbed5b 100644
--- a/src/qml/jsruntime/qv4lookup.cpp
+++ b/src/qml/jsruntime/qv4lookup.cpp
@@ -205,7 +205,7 @@ void Lookup::getterAccessor0(Lookup *l, Value *result, const Value &object)
             } else {
                 ScopedCallData callData(o->engine(), 0);
                 callData->thisObject = object;
-                res = getter->call(callData);
+                res = Value::fromReturnedValue(getter->call(callData));
             }
             if (result)
                 *result = res;
@@ -228,7 +228,7 @@ void Lookup::getterAccessor1(Lookup *l, Value *result, const Value &object)
             } else {
                 ScopedCallData callData(o->engine(), 0);
                 callData->thisObject = object;
-                res = getter->call(callData);
+                res = Value::fromReturnedValue(getter->call(callData));
             }
             if (result)
                 *result = res;
@@ -254,7 +254,7 @@ void Lookup::getterAccessor2(Lookup *l, Value *result, const Value &object)
                     } else {
                         ScopedCallData callData(o->engine(), 0);
                         callData->thisObject = object;
-                        res = getter->call(callData);
+                        res = Value::fromReturnedValue(getter->call(callData));
                     }
                     if (result)
                         *result = res;
@@ -309,7 +309,7 @@ void Lookup::primitiveGetterAccessor0(Lookup *l, Value *result, const Value &obj
             } else {
                 ScopedCallData callData(o->engine(), 0);
                 callData->thisObject = object;
-                res = getter->call(callData);
+                res = Value::fromReturnedValue(getter->call(callData));
             }
             if (result)
                 *result = res;
@@ -333,7 +333,7 @@ void Lookup::primitiveGetterAccessor1(Lookup *l, Value *result, const Value &obj
             } else {
                 ScopedCallData callData(o->engine(), 0);
                 callData->thisObject = object;
-                res = getter->call(callData);
+                res = Value::fromReturnedValue(getter->call(callData));
             }
             if (result)
                 *result = res;
@@ -437,7 +437,7 @@ void Lookup::globalGetterAccessor0(Lookup *l, ExecutionContext *ctx, Value *resu
         } else {
             ScopedCallData callData(ctx->engine, 0);
             callData->thisObject = Value::undefinedValue();
-            *result = getter->call(callData);
+            *result = Value::fromReturnedValue(getter->call(callData));
         }
         return;
     }
@@ -456,7 +456,7 @@ void Lookup::globalGetterAccessor1(Lookup *l, ExecutionContext *ctx, Value *resu
         } else {
             ScopedCallData callData(ctx->engine, 0);
             callData->thisObject = Value::undefinedValue();
-            *result = getter->call(callData);
+            *result = Value::fromReturnedValue(getter->call(callData));
         }
         return;
     }
@@ -478,7 +478,7 @@ void Lookup::globalGetterAccessor2(Lookup *l, ExecutionContext *ctx, Value *resu
                 } else {
                     ScopedCallData callData(ctx->engine, 0);
                     callData->thisObject = Value::undefinedValue();
-                    *result = getter->call(callData);
+                    *result = Value::fromReturnedValue(getter->call(callData));
                 }
                 return;
             }
diff --git a/src/qml/jsruntime/qv4managed.cpp b/src/qml/jsruntime/qv4managed.cpp
index 62491ba7e5..1a86889373 100644
--- a/src/qml/jsruntime/qv4managed.cpp
+++ b/src/qml/jsruntime/qv4managed.cpp
@@ -181,7 +181,7 @@ Value Managed::construct(Managed *m, CallData *)
     m->engine()->current->throwTypeError();
 }
 
-Value Managed::call(Managed *m, CallData *)
+ReturnedValue Managed::call(Managed *m, CallData *)
 {
     m->engine()->current->throwTypeError();
 }
diff --git a/src/qml/jsruntime/qv4managed_p.h b/src/qml/jsruntime/qv4managed_p.h
index 50325478f5..a71ee717db 100644
--- a/src/qml/jsruntime/qv4managed_p.h
+++ b/src/qml/jsruntime/qv4managed_p.h
@@ -91,7 +91,7 @@ struct CallData
 
 struct ManagedVTable
 {
-    Value (*call)(Managed *, CallData *data);
+    ReturnedValue (*call)(Managed *, CallData *data);
     Value (*construct)(Managed *, CallData *data);
     void (*markObjects)(Managed *);
     void (*destroy)(Managed *);
@@ -253,7 +253,7 @@ public:
         return vtbl->hasInstance(this, v);
     }
     Value construct(CallData *d);
-    Value call(CallData *d);
+    ReturnedValue call(CallData *d);
     Value get(String *name, bool *hasProperty = 0);
     Value getIndexed(uint index, bool *hasProperty = 0);
     void put(String *name, const Value &value)
@@ -282,7 +282,7 @@ public:
     static void destroy(Managed *that) { that->_data = 0; }
     static bool hasInstance(Managed *that, const Value &value);
     static Value construct(Managed *m, CallData *d);
-    static Value call(Managed *m, CallData *);
+    static ReturnedValue call(Managed *m, CallData *);
     static void getLookup(Managed *m, Lookup *, Value *);
     static void setLookup(Managed *m, Lookup *l, const Value &v);
     static bool isEqualTo(Managed *m, Managed *other);
diff --git a/src/qml/jsruntime/qv4numberobject.cpp b/src/qml/jsruntime/qv4numberobject.cpp
index e581bac35e..ce80d599ae 100644
--- a/src/qml/jsruntime/qv4numberobject.cpp
+++ b/src/qml/jsruntime/qv4numberobject.cpp
@@ -62,10 +62,10 @@ Value NumberCtor::construct(Managed *m, CallData *callData)
     return Value::fromObject(m->engine()->newNumberObject(Value::fromDouble(dbl)));
 }
 
-Value NumberCtor::call(Managed *, CallData *callData)
+ReturnedValue NumberCtor::call(Managed *, CallData *callData)
 {
     double dbl = callData->argc ? callData->args[0].toNumber() : 0.;
-    return Value::fromDouble(dbl);
+    return Value::fromDouble(dbl).asReturnedValue();
 }
 
 void NumberPrototype::init(ExecutionContext *ctx, const Value &ctor)
diff --git a/src/qml/jsruntime/qv4numberobject_p.h b/src/qml/jsruntime/qv4numberobject_p.h
index a0c2a65e80..a6e622e398 100644
--- a/src/qml/jsruntime/qv4numberobject_p.h
+++ b/src/qml/jsruntime/qv4numberobject_p.h
@@ -54,7 +54,7 @@ struct NumberCtor: FunctionObject
     NumberCtor(ExecutionContext *scope);
 
     static Value construct(Managed *that, CallData *callData);
-    static Value call(Managed *, CallData *callData);
+    static ReturnedValue call(Managed *, CallData *callData);
 
 protected:
     static const ManagedVTable static_vtbl;
diff --git a/src/qml/jsruntime/qv4object.cpp b/src/qml/jsruntime/qv4object.cpp
index c4c1b6f7f4..7236307278 100644
--- a/src/qml/jsruntime/qv4object.cpp
+++ b/src/qml/jsruntime/qv4object.cpp
@@ -137,7 +137,7 @@ Value Object::getValue(const Value &thisObject, const Property *p, PropertyAttri
 
     ScopedCallData callData(getter->engine(), 0);
     callData->thisObject = thisObject;
-    return getter->call(callData);
+    return Value::fromReturnedValue(getter->call(callData));
 }
 
 void Object::putValue(Property *pd, PropertyAttributes attrs, const Value &value)
diff --git a/src/qml/jsruntime/qv4objectproto.cpp b/src/qml/jsruntime/qv4objectproto.cpp
index cba8141257..5dc4d333ce 100644
--- a/src/qml/jsruntime/qv4objectproto.cpp
+++ b/src/qml/jsruntime/qv4objectproto.cpp
@@ -93,11 +93,11 @@ Value ObjectCtor::construct(Managed *that, CallData *callData)
     return Value::fromReturnedValue(__qmljs_to_object(v4->current, ValueRef(&callData->args[0])));
 }
 
-Value ObjectCtor::call(Managed *m, CallData *callData)
+ReturnedValue ObjectCtor::call(Managed *m, CallData *callData)
 {
     if (!callData->argc || callData->args[0].isUndefined() || callData->args[0].isNull())
-        return Value::fromObject(m->engine()->newObject());
-    return Value::fromReturnedValue(__qmljs_to_object(m->engine()->current, ValueRef(&callData->args[0])));
+        return Value::fromObject(m->engine()->newObject()).asReturnedValue();
+    return __qmljs_to_object(m->engine()->current, ValueRef(&callData->args[0]));
 }
 
 void ObjectPrototype::init(ExecutionContext *ctx, const Value &ctor)
@@ -388,7 +388,7 @@ Value ObjectPrototype::method_toLocaleString(SimpleCallContext *ctx)
         ctx->throwTypeError();
     ScopedCallData callData(ctx->engine, 0);
     callData->thisObject = Value::fromObject(o);
-    return f->call(callData);
+    return Value::fromReturnedValue(f->call(callData));
 }
 
 Value ObjectPrototype::method_valueOf(SimpleCallContext *ctx)
diff --git a/src/qml/jsruntime/qv4objectproto_p.h b/src/qml/jsruntime/qv4objectproto_p.h
index 33a115f203..06f88db656 100644
--- a/src/qml/jsruntime/qv4objectproto_p.h
+++ b/src/qml/jsruntime/qv4objectproto_p.h
@@ -54,7 +54,7 @@ struct ObjectCtor: FunctionObject
     ObjectCtor(ExecutionContext *scope);
 
     static Value construct(Managed *that, CallData *callData);
-    static Value call(Managed *that, CallData *callData);
+    static ReturnedValue call(Managed *that, CallData *callData);
 
 protected:
     static const ManagedVTable static_vtbl;
diff --git a/src/qml/jsruntime/qv4qobjectwrapper.cpp b/src/qml/jsruntime/qv4qobjectwrapper.cpp
index 10a2c3de44..0ccb37f48b 100644
--- a/src/qml/jsruntime/qv4qobjectwrapper.cpp
+++ b/src/qml/jsruntime/qv4qobjectwrapper.cpp
@@ -1688,10 +1688,10 @@ QV4::Value QObjectMethod::method_destroy(QV4::ExecutionContext *ctx, const Value
     return QV4::Value::undefinedValue();
 }
 
-Value QObjectMethod::call(Managed *m, CallData *callData)
+ReturnedValue QObjectMethod::call(Managed *m, CallData *callData)
 {
     QObjectMethod *This = static_cast<QObjectMethod*>(m);
-    return This->callInternal(callData);
+    return This->callInternal(callData).asReturnedValue();
 }
 
 Value QObjectMethod::callInternal(CallData *callData)
diff --git a/src/qml/jsruntime/qv4qobjectwrapper_p.h b/src/qml/jsruntime/qv4qobjectwrapper_p.h
index 895a7e3dad..4034e14cf5 100644
--- a/src/qml/jsruntime/qv4qobjectwrapper_p.h
+++ b/src/qml/jsruntime/qv4qobjectwrapper_p.h
@@ -141,7 +141,7 @@ private:
     int m_index;
     QV4::PersistentValue m_qmlGlobal;
 
-    static Value call(Managed *, CallData *callData);
+    static ReturnedValue call(Managed *, CallData *callData);
 
     Value callInternal(CallData *callData);
 
diff --git a/src/qml/jsruntime/qv4regexpobject.cpp b/src/qml/jsruntime/qv4regexpobject.cpp
index 448d10180c..7497b3e1ba 100644
--- a/src/qml/jsruntime/qv4regexpobject.cpp
+++ b/src/qml/jsruntime/qv4regexpobject.cpp
@@ -275,14 +275,14 @@ Value RegExpCtor::construct(Managed *m, CallData *callData)
     return Value::fromObject(o);
 }
 
-Value RegExpCtor::call(Managed *that, CallData *callData)
+ReturnedValue RegExpCtor::call(Managed *that, CallData *callData)
 {
     if (callData->argc > 0 && callData->args[0].as<RegExpObject>()) {
         if (callData->argc == 1 || callData->args[1].isUndefined())
-            return callData->args[0];
+            return callData->args[0].asReturnedValue();
     }
 
-    return construct(that, callData);
+    return construct(that, callData).asReturnedValue();
 }
 
 void RegExpPrototype::init(ExecutionContext *ctx, const Value &ctor)
diff --git a/src/qml/jsruntime/qv4regexpobject_p.h b/src/qml/jsruntime/qv4regexpobject_p.h
index a17802e2ff..cbf185ebf0 100644
--- a/src/qml/jsruntime/qv4regexpobject_p.h
+++ b/src/qml/jsruntime/qv4regexpobject_p.h
@@ -106,7 +106,7 @@ struct RegExpCtor: FunctionObject
     RegExpCtor(ExecutionContext *scope);
 
     static Value construct(Managed *m, CallData *callData);
-    static Value call(Managed *that, CallData *callData);
+    static ReturnedValue call(Managed *that, CallData *callData);
 
 protected:
     static const ManagedVTable static_vtbl;
diff --git a/src/qml/jsruntime/qv4runtime.cpp b/src/qml/jsruntime/qv4runtime.cpp
index 6771ee752f..a6fc9f8967 100644
--- a/src/qml/jsruntime/qv4runtime.cpp
+++ b/src/qml/jsruntime/qv4runtime.cpp
@@ -575,7 +575,7 @@ ReturnedValue __qmljs_object_default_value(Object *object, int typeHint)
     if (FunctionObject *o = conv.asFunctionObject()) {
         ScopedCallData callData(engine, 0);
         callData->thisObject = Value::fromObject(object);
-        Value r = o->call(callData);
+        Value r = Value::fromReturnedValue(o->call(callData));
         if (r.isPrimitive())
             return r.asReturnedValue();
     }
@@ -584,7 +584,7 @@ ReturnedValue __qmljs_object_default_value(Object *object, int typeHint)
     if (FunctionObject *o = conv.asFunctionObject()) {
         ScopedCallData callData(engine, 0);
         callData->thisObject = Value::fromObject(object);
-        Value r = o->call(callData);
+        Value r = Value::fromReturnedValue(o->call(callData));
         if (r.isPrimitive())
             return r.asReturnedValue();
     }
@@ -940,9 +940,9 @@ ReturnedValue __qmljs_call_global_lookup(ExecutionContext *context, uint index,
         context->throwTypeError();
 
     if (o == context->engine->evalFunction && l->name->isEqualTo(context->engine->id_eval))
-        return static_cast<EvalFunction *>(o)->evalCall(callData->thisObject, callData->args, callData->argc, true).asReturnedValue();
+        return static_cast<EvalFunction *>(o)->evalCall(callData->thisObject, callData->args, callData->argc, true);
 
-    return o->call(callData).asReturnedValue();
+    return o->call(callData);
 }
 
 
@@ -966,10 +966,10 @@ ReturnedValue __qmljs_call_activation_property(ExecutionContext *context, String
     }
 
     if (o == context->engine->evalFunction && name->isEqualTo(context->engine->id_eval)) {
-        return static_cast<EvalFunction *>(o)->evalCall(callData->thisObject, callData->args, callData->argc, true).asReturnedValue();
+        return static_cast<EvalFunction *>(o)->evalCall(callData->thisObject, callData->args, callData->argc, true);
     }
 
-    return o->call(callData).asReturnedValue();
+    return o->call(callData);
 }
 
 ReturnedValue __qmljs_call_property(ExecutionContext *context, String *name, CallDataRef callData)
@@ -991,7 +991,7 @@ ReturnedValue __qmljs_call_property(ExecutionContext *context, String *name, Cal
         context->throwTypeError(error);
     }
 
-    return o->call(callData).asReturnedValue();
+    return o->call(callData);
 }
 
 ReturnedValue __qmljs_call_property_lookup(ExecutionContext *context, uint index, CallDataRef callData)
@@ -1005,7 +1005,7 @@ ReturnedValue __qmljs_call_property_lookup(ExecutionContext *context, uint index
     if (!o)
         context->throwTypeError();
 
-    return o->call(callData).asReturnedValue();
+    return o->call(callData);
 }
 
 ReturnedValue __qmljs_call_element(ExecutionContext *context, const ValueRef index, CallDataRef callData)
@@ -1017,7 +1017,7 @@ ReturnedValue __qmljs_call_element(ExecutionContext *context, const ValueRef ind
     if (!o)
         context->throwTypeError();
 
-    return o->call(callData).asReturnedValue();
+    return o->call(callData);
 }
 
 ReturnedValue __qmljs_call_value(ExecutionContext *context, const ValueRef func, CallDataRef callData)
@@ -1026,7 +1026,7 @@ ReturnedValue __qmljs_call_value(ExecutionContext *context, const ValueRef func,
     if (!o)
         context->throwTypeError();
 
-    return o->call(callData).asReturnedValue();
+    return o->call(callData);
 }
 
 
diff --git a/src/qml/jsruntime/qv4script.cpp b/src/qml/jsruntime/qv4script.cpp
index 23d84a8b47..57938ff5b7 100644
--- a/src/qml/jsruntime/qv4script.cpp
+++ b/src/qml/jsruntime/qv4script.cpp
@@ -79,7 +79,7 @@ struct QmlBindingWrapper : FunctionObject
         scope->engine->popContext();
     }
 
-    static Value call(Managed *that, CallData *);
+    static ReturnedValue call(Managed *that, CallData *);
     static void markObjects(Managed *m)
     {
         QmlBindingWrapper *wrapper = static_cast<QmlBindingWrapper*>(m);
@@ -122,7 +122,7 @@ struct CompilationUnitHolder : public QV4::Object
 
 DEFINE_MANAGED_VTABLE(CompilationUnitHolder);
 
-Value QmlBindingWrapper::call(Managed *that, CallData *)
+ReturnedValue QmlBindingWrapper::call(Managed *that, CallData *)
 {
     ExecutionEngine *engine = that->engine();
     ValueScope scope(engine);
@@ -134,7 +134,7 @@ Value QmlBindingWrapper::call(Managed *that, CallData *)
     ScopedValue result(scope, This->function->code(ctx, This->function->codeData));
     engine->popContext();
 
-    return result;
+    return result.asReturnedValue();
 
 }
 
@@ -252,7 +252,7 @@ Value Script::run()
         FunctionObject *f = new (engine->memoryManager) QmlBindingWrapper(scope, vmFunction, qml.value().asObject());
         ScopedCallData callData(scope->engine, 0);
         callData->thisObject = Value::undefinedValue();
-        return f->call(callData);
+        return Value::fromReturnedValue(f->call(callData));
     }
 }
 
diff --git a/src/qml/jsruntime/qv4sequenceobject.cpp b/src/qml/jsruntime/qv4sequenceobject.cpp
index 058964969c..529c395c26 100644
--- a/src/qml/jsruntime/qv4sequenceobject.cpp
+++ b/src/qml/jsruntime/qv4sequenceobject.cpp
@@ -354,12 +354,13 @@ public:
         bool operator()(typename Container::value_type lhs, typename Container::value_type rhs)
         {
             QV4::Managed *fun = this->m_compareFn.asManaged();
+            ValueScope scope(fun->engine());
             ScopedCallData callData(fun->engine(), 2);
             callData->args[0] = convertElementToValue(this->m_ctx->engine, lhs);
             callData->args[1] = convertElementToValue(this->m_ctx->engine, rhs);
             callData->thisObject = QV4::Value::fromObject(this->m_ctx->engine->globalObject);
-            QV4::Value result = fun->call(callData);
-            return result.toNumber() < 0;
+            QV4::ScopedValue result(scope, fun->call(callData));
+            return result->toNumber() < 0;
         }
 
     private:
diff --git a/src/qml/jsruntime/qv4stringobject.cpp b/src/qml/jsruntime/qv4stringobject.cpp
index d595533714..b66ee6c180 100644
--- a/src/qml/jsruntime/qv4stringobject.cpp
+++ b/src/qml/jsruntime/qv4stringobject.cpp
@@ -170,14 +170,14 @@ Value StringCtor::construct(Managed *m, CallData *callData)
     return Value::fromObject(m->engine()->newStringObject(value));
 }
 
-Value StringCtor::call(Managed *m, CallData *callData)
+ReturnedValue StringCtor::call(Managed *m, CallData *callData)
 {
     Value value;
     if (callData->argc)
         value = Value::fromString(callData->args[0].toString(m->engine()->current));
     else
         value = Value::fromString(m->engine()->current, QString());
-    return value;
+    return value.asReturnedValue();
 }
 
 void StringPrototype::init(ExecutionEngine *engine, const Value &ctor)
@@ -351,6 +351,7 @@ Value StringPrototype::method_match(SimpleCallContext *context)
     if (context->thisObject.isUndefined() || context->thisObject.isNull())
         context->throwTypeError();
 
+    ValueScope scope(context);
     String *s = context->thisObject.toString(context);
 
     Value regexp = context->argumentCount ? context->arguments[0] : Value::undefinedValue();
@@ -374,7 +375,7 @@ Value StringPrototype::method_match(SimpleCallContext *context)
     callData->thisObject = Value::fromObject(rx);
     callData->args[0] = Value::fromString(s);
     if (!global)
-        return exec->call(callData);
+        return Value::fromReturnedValue(exec->call(callData));
 
     String *lastIndex = context->engine->newString(QStringLiteral("lastIndex"));
     rx->put(lastIndex, Value::fromInt32(0));
@@ -382,11 +383,13 @@ Value StringPrototype::method_match(SimpleCallContext *context)
 
     double previousLastIndex = 0;
     uint n = 0;
+    ScopedValue result(scope);
+    ScopedValue matchStr(scope);
     while (1) {
-        Value result = exec->call(callData);
-        if (result.isNull())
+        result = exec->call(callData);
+        if (result->isNull())
             break;
-        assert(result.isObject());
+        assert(result->isObject());
         double thisIndex = rx->get(lastIndex, 0).toInteger();
         if (previousLastIndex == thisIndex) {
             previousLastIndex = thisIndex + 1;
@@ -394,7 +397,7 @@ Value StringPrototype::method_match(SimpleCallContext *context)
         } else {
             previousLastIndex = thisIndex;
         }
-        Value matchStr = result.objectValue()->getIndexed(0);
+        matchStr = result->objectValue()->getIndexed(0);
         a->arraySet(n, matchStr);
         ++n;
     }
@@ -452,6 +455,7 @@ static void appendReplacementString(QString *result, const QString &input, const
 
 Value StringPrototype::method_replace(SimpleCallContext *ctx)
 {
+    ValueScope scope(ctx);
     QString string;
     if (StringObject *thisString = ctx->thisObject.asStringObject())
         string = thisString->value.stringValue()->toQString();
@@ -507,6 +511,7 @@ Value StringPrototype::method_replace(SimpleCallContext *ctx)
 
     QString result;
     Value replaceValue = ctx->argument(1);
+    ScopedValue replacement(scope);
     if (FunctionObject* searchCallback = replaceValue.asFunctionObject()) {
         result.reserve(string.length() + 10*numStringMatches);
         ScopedCallData callData(ctx->engine, numCaptures + 2);
@@ -528,9 +533,9 @@ Value StringPrototype::method_replace(SimpleCallContext *ctx)
             callData->args[numCaptures] = Value::fromUInt32(matchStart);
             callData->args[numCaptures + 1] = Value::fromString(ctx, string);
 
-            Value replacement = searchCallback->call(callData);
+            replacement = searchCallback->call(callData);
             result += string.midRef(lastEnd, matchStart - lastEnd);
-            result += replacement.toString(ctx)->toQString();
+            result += replacement->toString(ctx)->toQString();
             lastEnd = matchEnd;
         }
         result += string.midRef(lastEnd);
diff --git a/src/qml/jsruntime/qv4stringobject_p.h b/src/qml/jsruntime/qv4stringobject_p.h
index f9cf89e9d9..702900bb36 100644
--- a/src/qml/jsruntime/qv4stringobject_p.h
+++ b/src/qml/jsruntime/qv4stringobject_p.h
@@ -71,7 +71,7 @@ struct StringCtor: FunctionObject
     StringCtor(ExecutionContext *scope);
 
     static Value construct(Managed *m, CallData *callData);
-    static Value call(Managed *that, CallData *callData);
+    static ReturnedValue call(Managed *that, CallData *callData);
 
 protected:
     static const ManagedVTable static_vtbl;
diff --git a/src/qml/jsruntime/qv4value.cpp b/src/qml/jsruntime/qv4value.cpp
index 0347188ae0..6a717cde8d 100644
--- a/src/qml/jsruntime/qv4value.cpp
+++ b/src/qml/jsruntime/qv4value.cpp
@@ -327,6 +327,11 @@ PersistentValue::PersistentValue(const Value &val)
 {
 }
 
+PersistentValue::PersistentValue(ReturnedValue val)
+    : d(new PersistentValuePrivate(Value::fromReturnedValue(val)))
+{
+}
+
 PersistentValue::PersistentValue(const PersistentValue &other)
     : d(other.d)
 {
@@ -360,6 +365,16 @@ PersistentValue &PersistentValue::operator =(const Value &other)
     return *this;
 }
 
+PersistentValue &PersistentValue::operator =(const ReturnedValue &other)
+{
+    if (!d) {
+        d = new PersistentValuePrivate(Value::fromReturnedValue(other));
+        return *this;
+    }
+    d = d->detach(Value::fromReturnedValue(other));
+    return *this;
+}
+
 PersistentValue::~PersistentValue()
 {
     if (d)
diff --git a/src/qml/jsruntime/qv4value_p.h b/src/qml/jsruntime/qv4value_p.h
index 8d6f26ea57..ecd0c319b9 100644
--- a/src/qml/jsruntime/qv4value_p.h
+++ b/src/qml/jsruntime/qv4value_p.h
@@ -279,7 +279,7 @@ inline ErrorObject *Value::asErrorObject() const
 inline Value Managed::construct(CallData *d) {
     return vtbl->construct(this, d);
 }
-inline Value Managed::call(CallData *d) {
+inline ReturnedValue Managed::call(CallData *d) {
     return vtbl->call(this, d);
 }
 
@@ -311,10 +311,13 @@ class Q_QML_EXPORT PersistentValue
 {
 public:
     PersistentValue() : d(0) {}
+
     PersistentValue(const Value &val);
+    PersistentValue(ReturnedValue val);
     PersistentValue(const PersistentValue &other);
     PersistentValue &operator=(const PersistentValue &other);
     PersistentValue &operator=(const Value &other);
+    PersistentValue &operator =(const ReturnedValue &other);
     ~PersistentValue();
 
     Value value() const {